The present invention relates to communication systems and, more particularly to a method and apparatus for establishing a virtual facility connection whereby services provided by a main location private branch exchange (PBX) are accessible by affiliated or remotely located terminals via a concentrator, such as a relatively small on premises asynchronous transmission mode (ATM) switch, that transmits/receives control signals to or from the PBX over the Internet or a private data network.
The communication needs (voice and data) of relatively large companies often require interconnecting private branch exchanges (PBXs) and/or key telephone systems (KTSs) at multiple locations. Previously, tapping into services of a main location PBX from affiliated or remotely located terminals required the use of permanent off premises extensions via private tie line connections. Private tie line extensions are disadvantageous in that they have limited capabilities and PBX networking is generally impracticable in that it is too expensive for relatively small affiliate or remote locations.
It is therefore desirable to develop a system to allow terminals in affiliate or remote locations to tap into the services and features, such as networking, watts lines, high functionality sets, data and messaging services, provided by a main location PBX without incurring the expense of private tie lines.
An exemplary embodiment of a system for accessing services of a main location private branch exchange by a terminal at a remote location, in accordance with the present invention, includes a concentrator for formatting a message transmitted from the remote terminal to the main location private branch exchange as an Internet message, and for unformatting an Internet formatted message transmitted from the main location private branch exchange to the remote terminal.
In another embodiment, a control message generated by the remote terminal is formatted by a concentrator as an Internet message when the remote terminal goes off hook. The formatted Internet message is then routed over a path including a connection link, a public network and an Internet interface. Thereafter, the formatted message is unformatted and transmitted to the main location private branch exchange. In a preferred embodiment the formatted message is unformatted using a server or software provided in the main location private branch.
The present invention is also directed to a method for providing access to services of a main location private branch exchange by a terminal at a remote location using the device as described above. A message transmitted from a remote terminal to the main location private branch exchange are formatted as an Internet message, and a message transmitted from the main location private branch exchange to the remote terminal is unformatted using a concentrator.